TheSkySearchers

With my recent outings using my Explore Scientific ED-102, I ran into a couple issues with focus distance.

Using a standard 2" EP (in this case, an ES 25mm 70-degree EP) and a quality William Optics 2" diagonal, focus could not be achieved through the EP without the use of a tube extender. I was also able to get focus if I lifted the EP up in the diagonal a little bit. I happened to have 2" extenders, so it was not that much of a problem visually, and the views with the combination were stellar (pun intended).

Determined to get some pics of the Great Nebula, I elected to try using the Celestron Nightscape 8300 camera. The software loaded fine, the camera operated fine, but it seemed that no combination of extenders I had would get this into focus. Fidgeting around at sub 20 degree weather, I got close, but not close enough. I wanted to just get it focused/framed and let a few dozen/hundred snaps go to disk.

I am also a bit concerned with flexure from the focuser and a bunch of extension tubes. This is the stock focuser in the 102. The 8300 is not a light thing. I was hoping not to need a new Moonlite focuser for her.

I do have one of the Astro Tech 0.8x focal reducers (not mounted) on the shelf, but never used it.
Will this spare me external tube differences?

This is the older (it is 2 or 3 years old) ED-102. It is a 714mm focal length scope.

I would be interested in some feedback here. I have never had problems with my SCTs, or even the SNs in the past. It just seems like they made the tube a little short.

It is quite common for ED/APO scopes to make tube shorter than needed for EPs. This is to accommodate cameras for AP. Typically you would need 2" extension tube to get EPs in focus and you remove the extension tube to achieve the focus with camera.

I often lift the eyepiece up in the diagonal instead of having to insert an extender. Not a problem for visual, I think.

I had to tune my ED127CF focuser. If you take the focuser wheel off the focuser you may see some hidden setting screws. Check those and tighten them if needed. Higher up where the inner tube slides into the end of the focuser tube there may also be some setting screws, same story. To make those screws work better and add stability, add an extender so the upper part of the inner tube is always covered by setting screws. After I did all this my focuser worked much better, and I never had to re-adjust anything. Search CN for this (not my post but someone else's with pictures).

If you switch from visual to AP you generally need fewer extenders. You may want to remove the diagonal, that should help a bunch too. I hope your camera has an articulating screen.